217621212 has 48 divisors (see below), whose sum is σ = 538487040. Its totient is φ = 68211072.

The previous prime is 217621189. The next prime is 217621213. The reversal of 217621212 is 212126712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217621213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27753 + ... + 34719.

It is an arithmetic number, because the mean of its divisors is an integer number (11218480).

Almost surely, 2^217621212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217621212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (269243520).

217621212 is an abundant number, since it is smaller than the sum of its proper divisors (320865828).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217621212 is a wasteful number, since it uses less digits than its factorization.

217621212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7130 (or 7128 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 217621212 is about 14751.9901030336. The cubic root of 217621212 is about 601.4973821912.

Adding to 217621212 its reverse (212126712), we get a palindrome (429747924).

The spelling of 217621212 in words is "two hundred seventeen million, six hundred twenty-one thousand, two hundred twelve".